I play guitar in an acoustic trio (vocalist, steelstring-guitar, double bass).
Currently I use 7 different open tunings in the setlist.
So I have to retune quite often, and we have to deal with the breaks in our performance.
I use a stompbox tuner, tuning to 440Hz, so our bass player will stay in tune.

What practical solutions for dealing with different tunings are out there?
The goal is to mimimize the tuning breaks in our performance.

Taking our time and stories told by my band collegues (our current solution)?

Using 2 guitars - less retuning?

Using 2 guitars and a friend/guitar tech?

Using 7 guitars? Expensive...

Using mechanical tuners (banjo tuners, etc.) in order to speed up retuning?

8 Answers
8

There are really only three answers, and you've covered them in your question; with some extra choices within each one:

No on-stage tuning; no help

The only way to achieve this is with a separate guitar for each tuning.

No on-stage tuning; a helper

While you're playing, the helper is preparing your guitar for the next song. Obviously this requires at least two guitars.

If the tunings require different strings, you'll want a different guitar for each string set; it does not make sense to have someone re-stringing guitars during your set! Logic says you could do your set in any order if you had two guitars in each string configuration (so you can play one while your tech tunes the other), but if you plan your set around it you could probably get away with fewer.

On-stage tuning

Simply (!) practice retuning so that you can do it quickly. Avoid guitars that make this difficult, such as those with a floating bridge. For example, anyone with a decent ear should be able to retune from standard tuning to drop-D in a couple of seconds, without a tuner.

As with the off-stage tuning situation, you will need at least one guitar in each string configuration.

Only you know what set of tunings you're using, but you should be able to group them into families according to how much tuning it takes to go from one to another. If you have guitars to spare, take one per "tuning family" so that your set never involves retuning all six strings.

If you're amplified, run your guitar through a chromatic tuner, then to a volume pedal (or just a mute switch), then to the rest of your signal chain. That way you don't make your audience have to listen to you tuning - unless you want to make a feature of it.

Mechanical tuners, tuning wrenches etc. are useful when restringing a guitar, because there are so many turns sometimes between fitting the string and it being "almost there". For the few turns you'd be making between useful tunings on a guitar where the strings are already up to tension, I don't see any great advantage to them.

First thing you might consider is to re-arrange some of the pieces. You're probably hesitant to do that; I'm not saying you should somehow cramp all the pieces into standard tuning, but it's quite possible that once you've tried every piece in several different tunings you will find you can at least reduce the number a little – seven is really quite extreme.

If you're not getting around some on-stage tuning: especially in an acoustic trio, I don't think a stompbox tuner is ideal; tuning by ear gives, IMO, a far better image. Depending on the musical style you might either do it very concentrated and quietly, which gives a "classical", professional impression and should also keep the audience concentrated, or deliberately loud and determinate to create a casual atmosphere and allow the audience to relax while at the same time keeping their focus on the stage. An electronic tuner, on the other hand, tends to feel impersonal and gives the impression that you're not really "in the show".
Sure it's more difficult to tune by ear, but it doesn't need to be much of a risk; in doubt, ask the bass player for a note. Do practise the tuning procedure so that you get it done quickly, otherwise you won't be able to keep the audience's attention; and of course safely so it won't sound out of tune after two changes.

If your colleague who did the story-telling so far did that well, keep to it! Take your time, why not. There's seldom any reason not to make short breaks between two pieces, with a bit of talk; in fact it can much more quickly get difficult to follow your performance if there are no such breaks. A bit of humour can't hurt, even of the more stupid kind like the inevitable jokes about that ever-so-annoyingly-tuning guitarist.
As an extreme example, watch some Tommy Emmanuel performances.

The only real alternative that comes to mind is Joni Mitchell's solution. She is known for many many tuning changes, and her rig, last I heard, is a Parker Fly with a MIDI bridge and MIDI box that adjusts to her tunings, so it stays in standard but it sounds like DADGAD or whatever she chooses. It sounds like a great technical solution, but also a bit pricey. Cheaper to tell stories.

An alternative to the Parker Fly is the Line 6 Variax. They're about the price of a decent electric guitar -- not a rare one -- and give you a boatload of options. Not that I would ever presume to second guess a musical legend like Joni Mitchell.

If you can buy a new guitar, Gibson sells several electric guitars that have a computer-controlled mechanical device that automatically cranks each of the six tuners individually and retunes the guitar to any open tuning automatically according to how you program it. Gibson calls these various models "Robot guitars". There have been many models on the market in the last five years at various price points.

I would seriously look into the Line 6 Variax electric guitars. They do not physically retune the tension on the strings. Rather, they take a guitar in standard tuning and transpose the pitch of each string via digital signal processing to create open tunings. The other advantage is that these electric guitars do a good job of simulating the sounds of various acoustic guitars as well.

Both the Gibson and the Variax guitars can be found starting at around US $1,200, and you can find used ones on eBay.

Mark Kozelek changes the tuning between almost each song. He mainly just told stories about Red House Painters while he was tuning. I assumed it would be awkward between songs because I knew going in he used many different tunings. I would say plan the tunings in advance to minimize having to change all six strings, if you only have to change one or two, it'll get you playing faster.